Elevated tumor necrosis factor-alpha in skeletal muscle after stroke

Area of Science:

• Neuroscience
• Immunology
• Metabolism

Background:

• Tumor necrosis factor-alpha (TNF-alpha) is an inflammatory cytokine linked to muscle wasting and insulin resistance.
• Stroke is associated with muscle atrophy, diabetes, and insulin resistance.
• TNF-alpha expression in hemiparetic skeletal muscle has not been previously studied.

Purpose of the Study:

• To investigate elevated TNF-alpha mRNA levels in the paretic leg muscles of chronic ischemic stroke patients compared to non-paretic legs and healthy controls.
• To explore the role of inflammation in stroke-induced muscle changes.

Main Methods:

• Muscle biopsies were obtained from the vastus lateralis of 20 stroke patients and 9 controls.
• Total RNA was extracted, reverse transcribed to cDNA, and TNF-alpha transcripts were quantified using real-time quantitative polymerase chain reaction.
• TNF-alpha mRNA levels were normalized against a housekeeping gene (acidic ribosomal phosphoprotein).

Main Results:

• TNF-alpha mRNA levels were 2.8-fold higher in the paretic leg muscles of stroke patients compared to controls (P<0.03).
• Non-paretic leg muscles showed a 1.6-fold increase in TNF-alpha mRNA compared to controls (P<0.11).
• A trend towards higher TNF-alpha mRNA levels was observed in paretic versus non-paretic leg muscles.

Conclusions:

• Stroke patients exhibit increased TNF-alpha expression in their paretic leg muscles.
• These findings suggest that inflammatory pathways are activated in the skeletal muscle following stroke.
• Further research is warranted to determine if intramuscular TNF-alpha contributes to muscle atrophy and metabolic dysfunction post-stroke.